Warm-Ups Day 8 3.1

Which subatomic particle was discovered by J.J. Thomson?

• Proton

• Neutron

• Electron

• Nucleus

Answer explanation

J.J. Thomson discovered the electron in 1897 through his experiments with cathode rays, demonstrating that they were composed of negatively charged particles, which he named electrons.

Compare the Bohr model and the Rutherford model of the atom. Which of the following is a key difference?

• Bohr's model includes electron orbits, while Rutherford's does not.

• Rutherford's model includes electron orbits, while Bohr's does not.

• Both models include electron orbits.

• Neither model includes electron orbits.

Answer explanation

The key difference is that Bohr's model introduces the concept of fixed electron orbits around the nucleus, while Rutherford's model does not specify electron paths, only describing the nucleus and the surrounding space.

What is the charge of a neutron?

• Positive

• Negative

• Neutral

• Variable

Answer explanation

A neutron has no electric charge, making it neutral. This distinguishes it from protons, which are positively charged, and electrons, which are negatively charged.

In the context of atomic theory, what does the term "nucleus" refer to?

• The outer shell of an atom

• The center of an atom containing protons and neutrons

• The space where electrons are found

• The entire atom

Answer explanation

The term 'nucleus' refers to the center of an atom, which contains protons and neutrons. This distinguishes it from the outer shell where electrons are found, making the correct choice the center of an atom containing protons and neutrons.

Which of the following statements correctly describes the electron cloud model?

• Electrons orbit the nucleus in fixed paths.

• Electrons are found in specific, fixed locations.

• Electrons are found in regions of probability around the nucleus.

• Electrons are stationary around the nucleus.

Answer explanation

The electron cloud model describes electrons as being located in regions of probability around the nucleus, rather than in fixed paths or locations. This reflects the uncertainty in their exact position.

How did the discovery of the neutron contribute to the atomic model?

• It explained the atom's positive charge.

• It accounted for the missing mass in the nucleus.

• It explained the atom's negative charge.

• It showed that atoms are indivisible.

Answer explanation

The discovery of the neutron was crucial as it accounted for the missing mass in the nucleus, which could not be explained by protons alone. This helped refine the atomic model, leading to a better understanding of atomic structure.

Tags

NGSS.HS-PS1-8

Which of the following best describes the plum pudding model of the atom?

• Electrons orbit a dense nucleus.

• Electrons are embedded in a positively charged sphere.

• Electrons are in fixed orbits around the nucleus.

• Electrons are in a cloud around the nucleus.

Answer explanation

The plum pudding model, proposed by J.J. Thomson, describes the atom as a positively charged sphere with electrons embedded within it, resembling a pudding with plums. This contrasts with models that depict electrons in fixed orbits or clouds.

Which subatomic particle is not found in the nucleus of an atom?

• Proton

• Neutron

• Electron

• All of the above are found in the nucleus

What is the charge of a proton?

• Negative

• Positive

• Neutral

• Variable

the area outside the nucleus that contains the electrons

• electron cloud
• electron
• nucleus
• subatomic particle